Bearing assemblies including a thermally conductive structure, bearing apparatuses, and methods of use

ABSTRACT

Embodiments of the invention are directed to bearing assemblies configured to effectively provide heat distribution from and/or heat dissipation for bearing element, bearing apparatuses including such bearing assemblies, and methods of operating such bearing assemblies and apparatuses. In an embodiment, a bearing assembly includes a plurality of superhard bearing elements distributed about an axis. Each superhard bearing element of the plurality of superhard bearing elements has a superhard material including a superhard surface. Additionally, a support ring structure that includes a support ring that supports the plurality of superhard bearing elements and a thermally-conductive structure in thermal communication with the superhard table of each of the plurality of superhard bearing elements. The thermally-conductive structure has a higher thermal conductivity than the support ring of the support ring structure.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.14/309,376 filed on 19 Jun. 2014, which is a continuation of U.S.application Ser. No. 13/801,125 filed on 13 Mar. 2013 (now U.S. Pat. No.8,807,837 issued on 19 Aug. 2014), the contents of which areincorporated herein, in their entirety, by this reference.

BACKGROUND

Subterranean drilling systems that employ downhole drilling motors arecommonly used for drilling boreholes in the earth for oil and gasexploration and production. A subterranean drilling system typicallyincludes a downhole drilling motor that is operably connected to anoutput shaft. Bearing apparatuses (e.g., thrust, radial, tapered, andother types of bearings) also may be operably coupled to the downholedrilling motor. A rotary drill bit configured to engage a subterraneanformation and drill a borehole is connected to the output shaft. As theborehole is drilled with the rotary drill bit, pipe sections may beconnected to the subterranean drilling system to form a drill stringcapable of progressively drilling the borehole to a greater depth withinthe earth.

A typical bearing apparatus includes a stator that does not rotate and arotor that is attached to the output shaft and rotates with the outputshaft. The stator and rotor each includes a plurality of bearingelements, which may be fabricated from polycrystalline diamond compacts(“PDCs”) that provide diamond bearing surfaces that bear against eachother during use.

The operational lifetime of the bearing apparatuses often determines theuseful life of the subterranean drilling system. Therefore,manufacturers and users of subterranean drilling systems continue toseek improved bearing apparatuses to extend the useful life of suchbearing apparatuses.

SUMMARY

Embodiments of the invention are directed to bearing assembliesconfigured to effectively provide heat distribution from and/or heatdissipation for bearing elements, bearing apparatuses including suchbearing assemblies, and methods of operating such bearing assemblies andapparatuses. In an embodiment, a bearing assembly includes a pluralityof superhard bearing elements distributed about an axis. Each superhardbearing element of the plurality of superhard bearing elements includesa superhard material having a superhard bearing surface. The bearingassembly includes a support ring structure that includes a support ringthat supports the plurality of superhard bearing elements and athermally-conductive structure in thermal communication with thesuperhard material of each of the plurality of superhard bearingelements. The thermally-conductive structure has a higher thermalconductivity than the support ring of the support ring structure.

In an embodiment, a method of maintaining operating temperature ofsuperhard bearing elements, which form part of a bearing assembly, belowa selected temperature thereof is disclosed. The method includessupporting a plurality of superhard bearing elements by a support ringthat has a relatively low thermal conductivity. The method also includesselectively loading a first set of one or more superhard bearingelements of the plurality of superhard bearing elements in a manner thatthe first set of one or more superhard bearing elements experiences ahigher load than a second set of one or more superhard bearing elementsof the plurality of superhard bearing elements. Furthermore, the methodincludes transferring heat the first set of one or more superhardbearing elements to a thermally-conductive structure that has asubstantially higher thermal conductivity than the support ring.

In an embodiment, a bearing apparatus includes a first bearing assembly,which includes one or more first bearing surfaces, and a support ringcarrying the one or more first bearing surfaces. The bearing apparatusalso includes a second bearing assembly including a plurality ofsuperhard bearing elements. Moreover, each of the plurality of superhardbearing elements has a second superhard bearing surface positioned andoriented to engage the one or more first bearing surfaces of the firstbearing assembly. The second bearing assembly also has a support ringstructure securing the plurality of superhard bearing elements. Thesupport ring structure includes a support ring that supports theplurality of superhard bearing elements and a thermally-conductivestructure thermally connecting the plurality of superhard bearingelements to each other.

Features from any of the disclosed embodiments may be used incombination with one another, without limitation. In addition, otherfeatures and advantages of the present disclosure will become apparentto those of ordinary skill in the art through consideration of thefollowing detailed description and the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings illustrate several embodiments, wherein identical referencenumerals refer to identical or similar elements or features in differentviews or embodiments shown in the drawings.

FIG. 1 is an isometric view of a thrust-bearing apparatus according toan embodiment;

FIG. 2A is a top view of a thrust-bearing assembly according to anembodiment;

FIG. 2B is a cross-sectional view of the thrust-bearing assembly of FIG.2A;

FIG. 3A is a cross-sectional view of a thrust-bearing assembly accordingto another embodiment;

FIG. 3B is a cross-sectional view of a thrust-bearing assembly accordingto yet another embodiment;

FIG. 4 is a cross-sectional view of the thrust-bearing assemblyaccording to yet another embodiment;

FIG. 5 is an isometric view of a radial-bearing apparatus according toan embodiment;

FIG. 6A is an isometric cutaway view of a radial-bearing assembly shownin FIG. 5 according to an embodiment;

FIG. 6B is an isometric cutaway view of the radial-bearing assemblyshown in FIG. 5; and

FIG. 7 is an isometric view of a subterranean drilling system inaccordance with an embodiment.

DETAILED DESCRIPTION

Embodiments of the invention are directed to bearing assembliesconfigured to effectively provide heat distribution from and/or heatdissipation for bearing elements, bearing apparatuses including suchbearing assemblies, and methods of operating such bearing assemblies andapparatuses. In particular, one or more embodiments include a bearingapparatus, which may include a first and second bearing assemblies(e.g., a stator and a rotor) configured to engage one another, and whichmay provide heat distribution and/or dissipation across bearing elementsthat may comprise the first and/or second bearing assemblies. In someoperational conditions, one or more of the bearing elements may bepreferentially loaded, such as to carry preferentially higher radialand/or axial loads (i.e., structural loads). Additionally, it isbelieved that some of the bearing elements of the bearing assembly mayexperience increased friction or frictional load relative to otherbearing elements that comprise the same bearing assembly. It is alsobelieved that, under certain conditions, one or a several bearingelements may experience relatively high-loads, while other bearingelements may experience relatively low-loads. For example, the one ormore bearing elements in a thrust-bearing assembly may extend fartherout of plane (e.g., by 0.001″) relative to the other, bearing elementsand, thus, may experience higher forces and/or friction. In one example,certain bearing elements may experience a higher thermal load or mayheat up at an accelerated rate, as compared with other bearing elements,for reasons that are not currently fully understood.

Accelerated and/or uneven heating or thermal loading of the bearingelements may lead to premature failure of the bearing assembly. Forinstance, the bearing elements may include a superhard material, whichmay deteriorate and/or degrade, and experience failure at elevatedtemperatures that may result from such heating. In addition, thermalexpansion of the one or more bearing elements may increase forces on theone or more bearing elements during operation. In some instances,increased structural loading of the bearing elements may lead todeformation and/or fracturing of the bearing assembly and/or componentor elements thereof. In any case, accelerated and/or uneven heating ofthe bearing elements may prematurely cause damage thereto (e.g., bydamaging or degrading the superhard material that may comprises suchbearing elements), which may lead to the failure of the bearingassembly.

Accordingly, distributing heat among superhard bearing elements and/ordissipating heat therefrom may increase the useful life of the bearingassemblies and apparatuses, as provided in one or more embodimentsdisclosed herein. More specifically, a bearing assembly may incorporatea thermally-conductive structure, which may transfer heat between and/oramong multiple superhard bearing elements that form part of the bearingassembly. In an embodiment, one or more thermally-conductive structuresmay provide a thermal connection between one or more superhard bearingelements. Hence, in at least one embodiment, thermally-conductivestructures may at least partially redistribute the thermal load from oneor more bearing elements (e.g., among a plurality or all of the bearingelements that comprise the bearing assembly).

Additionally, in an embodiment, redistributing the thermal load from oneor several bearing elements among multiple bearing elements may helpshare or even substantially equalize thermal loads on the bearingelements of the bearing assembly. In other words, such redistributionmay produce substantially the same or similar temperature acrossselected bearing elements (e.g., all or substantially all of the bearingelements). As such, the collective heat capacity of selected bearingelements may be utilized to absorb heat produced during the operation ofthe bearing assembly. These selected bearing elements may furtherdissipate the heat to the cooling fluid.

In some instances, the bearing assembly may receive and/or generate moreheat in or near a first portion thereof (e.g., a portion closer toshaft), which may increase the temperature in the first portion of thebearing assembly, while the temperature in a second portion of thebearing assembly may remain at a lower temperature. Such uneventemperature distribution may warp the bearing assembly. Furthermore, insome situations, warping may inhibit or prevent hydrodynamic operationof the bearing apparatus and/or may unevenly load the superhard bearingelements. In an embodiment, the thermally-conductive structure canreduce or eliminate uneven heating of the bearing assembly, therebyreducing or eliminating warping thereof.

In one or more embodiments, the thermally conductive structures maygenerally provide temperature distribution across the bulk of thebearing assembly. That is, the thermally conductive structures mayreduce or eliminate uneven temperature distribution within elementsand/or components of the bearing assembly. Consequently, embodiments ofthe invention also may reduce thermal warping of the bearing assembly,which may increase the useful life thereof.

Accordingly, various embodiments disclosed herein involve bearingapparatuses and assemblies that may accommodate non-uniform structural,frictional, and/or thermal loading of bearing elements, such assuperhard bearing elements. Additionally, in some embodiments, thebearing apparatuses and assemblies may be employed in and/orincorporated into apparatuses for use in downhole, subterranean drillingsystems and other mechanical systems, as further described below.

FIG. 1 illustrates an embodiment of a thrust-bearing apparatus 100.Specifically, the thrust-bearing apparatus 100 may include first andsecond thrust-bearing assemblies 110, 120. The first thrust-bearingassembly 110 may be a stator that remains stationary, while the secondthrust-bearing assembly 120 may be a rotor that may rotate relative tothe stator, or vice versa.

Each of the first thrust-bearing assembly 110 and the secondthrust-bearing assembly 120 may include multiple generally opposingsuperhard bearing elements 130 (e.g., superhard bearing elements 130 a,130 b) that face and engage one another. As used herein, a “superhardbearing element” is a bearing element including a bearing surface thatis made from a material exhibiting a hardness that is at least as hardas tungsten carbide. In any of the embodiments disclosed herein, thesuperhard bearing elements may include one or more superhard materials,such as polycrystalline diamond, polycrystalline cubic boron nitride,silicon carbide, tungsten carbide, or any combination of the foregoingsuperhard materials.

Additionally, the superhard bearing elements 130 a, 130 b may havebearing surfaces 132, such as the bearing surfaces 132 a, 132 b,respectively. In particular, the bearing surfaces 132 a may generallyoppose and engage the bearing surfaces 132 b. As such, the superhardbearing elements 130 may prevent relative axial movement of the firstthrust-bearing assembly 110 and the second thrust-bearing assembly 120(along a thrust axis 10), while allowing the second thrust-bearingassembly 120 to rotate relative to the first thrust-bearing assembly 110about the thrust axis 10.

Moreover, the first thrust-bearing assembly 110 and the secondthrust-bearing assembly 120 may include openings, therein such as anopening 140 in the first thrust-bearing assembly 110. More specifically,a shaft, such as an output shaft of the subterranean drilling system,may fit through and/or may be secured within the openings 140. Forexample, the shaft may fit through the opening 140 of the firstthrust-bearing assembly 110 in a manner that the shaft may freely rotatewithin the opening 140 of the first thrust-bearing assembly 110.Additionally, the first thrust-bearing assembly 110 may be securedwithin and/or to an element or component of a machine that remainsstationary relative to the shaft (e.g., a housing of the subterraneandrilling system).

The shaft may be secured within the opening (not shown) of the secondthrust-bearing assembly 120. Hence, as the output shaft rotates, thefirst thrust-bearing assembly 110 may remain stationary and the secondthrust-bearing assembly 120 may rotate together with the output shaft.Consequently, as described below in further detail, the thrust-bearingapparatus 100 may allow the shaft to rotate about the thrust axis 10. Atthe same time, the thrust-bearing apparatus 100 may prevent or limitlinear axial movement of the shaft along the thrust axis 10 relative tothe stationary elements or components that secure the firstthrust-bearing assembly 110.

Although the thrust-bearing apparatus 100 described above mayincorporate multiple superhard bearing elements 130 that havecorresponding bearing surfaces 132, it should be appreciated that thisis one of many embodiments. For example, the first thrust-bearingassembly 110 and/or the second thrust-bearing assembly 120 may include asingle superhard bearing element that spans an entire circumferencethereof. In other words, the superhard bearing element may form a singleor substantially uninterrupted or continuous bearing surface that mayspan the entire circumference of the first and/or second thrust-bearingassemblies 110, 120. Furthermore, the first thrust-bearing assembly 110and/or the second thrust-bearing assembly 120 may have any number of thesuperhard bearing elements 130 that may be spaced apart from each otherin any desired configuration, which may vary from one embodiment toanother. For instance, in some embodiments, the superhard bearingelements 130 may overlap, interlock, or otherwise fit together or abutone another thereby forming a substantially continuous 132.

In additional or alternative embodiments, the thrust-bearing apparatusmay include only a single thrust-bearing bearing assembly (e.g., thefirst or second thrust-bearing assembly 110, 120). For example, thebearing surfaces 132 of the first thrust-bearing assembly 110 can engagea component or element of a machine, which may be stationary or may bemoveable relative to the first thrust-bearing assembly 110. In anembodiment, the bearing surfaces 132 of the first thrust-bearingassembly 110 may engage a substantially flat plate that may be securedto a rotating element or component of a machine or mechanism thatincorporates the first thrust-bearing assembly 110. Moreover, such platemay provide a bearing surface that, in some instances, may have a lowerhardness than the superhard bearing elements 130 of the first bearingassembly 110. For instance, the bearing surface of a plate opposing thefirst thrust-bearing assembly 110 can have a hardness of about 30-32HRc.

Except as described herein, the first thrust-bearing assembly 110 andits components and elements may be similar to or the same as the secondthrust-bearing assembly 120 and its respective components and elements.Accordingly, for ease of description, references to the thrust-bearingassembly 110, unless noted otherwise, shall be understood to be equallyapplicable to the thrust-bearing assembly 120. For instance, asdescribed above, the thrust-bearing assembly 110 may include athermally-conductive structure that provides thermal communicationbetween the superhard bearing elements 130. An embodiment of thethrust-bearing assembly 110 is illustrated in FIGS. 2A and 2B.

More specifically, as illustrated in FIG. 2A, the thrust-bearingassembly 110 includes a support ring structure 150 that carries thesuperhard bearing elements 130. As mentioned above, the support ringstructure 150 may form or define the opening 140 therein. In someembodiments, the opening 140 may have a substantially circular orcylindrical shape. Alternatively, the opening 140 may have any number ofsuitable shapes, which may vary from one embodiment to another. In anycase, the opening 140 may accommodate a shaft or other machine componentor element that may pass therethrough and/or may be secured thereto.Furthermore, in an embodiment, the support ring structure 150 may haveno openings 140.

Additionally, the support ring structure 150 may form or define an outerperimeter of the thrust-bearing assembly 110. Similar to the opening140, the outer perimeter formed by the support ring structure 150 alsomay have any number of suitable shapes. In an embodiment, the outerperimeter has a substantially circular shape. In other embodiments,however, the outer perimeter may have a rectangular, triangular,trapezoidal, or essentially any other shape.

As illustrated in FIG. 2B, the support ring structure 150 mayincorporate multiple elements or components. In one embodiment, thesupport ring structure 150 may include a support ring 151 and aretention ring 152. In some embodiments, the retention ring 152 may becoupled to the support ring 151. For example, the retention ring 152 andthe support ring 151 may be bolted, welded, brazed, soldered, orotherwise secured together (e.g., via press-fit configuration with eachother).

Furthermore, the retention ring 152 can couple or secure the superhardbearing elements 130 to the support ring structure 150. In additional oralternative embodiments, the support ring structure may be without theretention ring 152. Accordingly, in some embodiment, the superhardbearing elements 130 can be coupled directly to the support ring 151, asfurther described below.

In one or more embodiments, the superhard bearing elements 130 may havea shoulder that is retained by a corresponding portion of the retentionring 152 within corresponding recesses 153, in a manner that thesuperhard bearing elements 130 is held substantially fixed forstationary relative to the support ring structure 150. Additionally oralternatively, the superhard bearing elements 130 may be secured to thesupport ring structure 150 in any number of suitable ways that may varyfrom one embodiment to the next. For instance, the superhard bearingelements 130 may be secured within the recesses 153 partially thereinvia brazing, press-fitting, threadedly attaching, fastening with afastener, combinations of the foregoing, or another suitable technique.As noted above, the supporting ring structure 150 may have no retentionring 152. Consequently, in some embodiments, the recesses 153 may beformed or defined within the support ring 151.

The support ring 151 and/or retention ring 152 may include a variety ofdifferent materials, compounds, and combinations of materials. Forexample, the support ring 151 and retention ring 152 may include ametal, alloy steel, a metal alloy, carbon steel, stainless steel,tungsten carbide, and combinations thereof. As further described below,various portions of the support ring structure 150 (e.g., the supportring 151 and/or retention ring 152) may include any number of othersuitable or conductive, metallic, non-metallic, non-conductive, orsemiconductive materials. Furthermore, the support ring 151 and/or theretention ring 152 may include a material that has a relatively lowthermal conductivity, as compared to the thermal conductivity ofthermally-conductive materials. In any event, the support ring 151 mayinclude a suitable material, having sufficient strength and resilienceto support the superhard bearing elements 130.

The superhard bearing elements 130 may have any number of suitablearrangements on the supporting ring structure 150, which may vary fromone embodiment to another. For example, the superhard bearing elements130 may be circumferentially positioned about the thrust axis 10 on thesupporting ring structure 150. Moreover, the superhard bearing elements130 may be arranged in a single row about the support ring structure150. In additional or alternative embodiments, the superhard bearingelements 130 may be distributed in two rows, three rows, four rows, orany other number of rows.

In one or more embodiments, the superhard bearing elements 130 may bepre-machined to tolerances and mounted in the support ring structure150. Also, the superhard bearing elements 130 may be first mounted inthe support ring structure 150 and then planarized (e.g., by lappingand/or grinding) to form bearing surfaces 132 thereof, so that thebearing surfaces 132 are substantially coplanar. As mentioned above, insome instances, bearing surface 132 of one or more superhard bearingelements 130 may be out of plane relative to the bearing surfaces ofother superhard bearing elements. Optionally, one or more of thesuperhard bearing elements 130 may have a peripherally extending edgechamfer.

In at least one embodiment, the support ring structure 150 may include athermally-conductive structure 160, which may channel heat from one ormore of the superhard bearing elements 130 to other superhard bearingelements 130. For instance, the thermally-conductive structure 160 mayreduce an average thermal load of one or more superhard bearing elements130 and/or may reduce an average thermal load of all of the superhardbearing elements 130 by channeling and/or redistributing heat therefromamong many superhard bearing elements 130, substantially all superhardbearing elements 130, or all of the superhard bearing elements 130.Accordingly, the thermally-conductive structure 160 may reduce thetemperature of the superhard bearing elements 130 as well as prevent orlimit rapid temperature increases thereof.

As mentioned above, high thermal load may result from high force and/orfriction load experienced by certain superhard bearing elements 130. Byreducing the average thermal load of the superhard bearing elements 130,the thermally-conductive structure 160 also may allow the superhardbearing elements 130 to wear in, such that the bearing surfaces 132 ofthe one or more superhard bearing elements 130 may be substantiallycoplanar with some or all of the superhard bearing elements 130. Assuch, the thermally-conductive structure 160 also may facilitate awear-in period, while avoiding premature failure or degradation of thesuperhard bearing elements 130.

In some embodiments, the superhard bearing elements 130 may include asuperhard table 170 bonded to a substrate 180. For example, thesuperhard table 170 may comprise polycrystalline diamond and thesubstrate 180 may comprise cobalt-cemented tungsten carbide.Furthermore, in any of the embodiments disclosed herein, thepolycrystalline diamond table may be leached to at least partiallyremove or substantially completely remove a metal-solvent catalyst(e.g., cobalt, iron, nickel, or alloys thereof) that was used toinitially sinter precursor diamond particles to form the polycrystallinediamond. In another embodiment, an infiltrant used to re-infiltrate apreformed leached polycrystalline diamond table may be leached orotherwise removed to a selected depth from a bearing surface. Moreover,in any of the embodiments disclosed herein, the polycrystalline diamondmay be un-leached and include a metal-solvent catalyst (e.g., cobalt,iron, nickel, or alloys thereof) that was used to initially sinter theprecursor diamond particles that form the polycrystalline diamond and/oran infiltrant used to re-infiltrate a preformed leached polycrystallinediamond table. Examples of methods for fabricating the superhard bearingelements and superhard materials and/or structures from which thesuperhard bearing elements may be made are disclosed in U.S. Pat. Nos.7,866,418; 7,998,573; 8,034,136; and 8,236,074; the disclosure of eachof the foregoing patents is incorporated herein, in its entirety, bythis reference.

The diamond particles that may be used to fabricate the superhard table170 in a high-pressure/high-temperature process (“HPHT)” may exhibit alarger size and at least one relatively smaller size. As used herein,the phrases “relatively larger” and “relatively smaller” refer toparticle sizes (by any suitable method) that differ by at least a factorof two (e.g., 30 μm and 15 μm). According to various embodiments, thediamond particles may include a portion exhibiting a relatively largersize (e.g., 70 μm, 60 μm, 50 μm, 40 μm, 30 μm, 20 μm, 15 μm, 12 μm, 10μm, 8 μm) and another portion exhibiting at least one relatively smallersize (e.g., 15 μm, 12 μm, 10 μm, 8 μm, 6 μm, 5 μm, 4 μm, 3 μm, 2 μm, 1μm, 0.5 μm, less than 0.5 μm, 0.1 μm, less than 0.1 μm). In anembodiment, the diamond particles may include a portion exhibiting arelatively larger size between about 10 μm and about 40 μm and anotherportion exhibiting a relatively smaller size between about 1 μm and 4μm. In another embodiment, the diamond particles may include a portionexhibiting the relatively larger size between about 15 μm and about 50μm and another portion exhibiting the relatively smaller size betweenabout 5 μm and about 15 μm. In another embodiment, the relatively largersize diamond particles may have a ratio to the relatively smaller sizediamond particles of at least 1.5. In some embodiments, the diamondparticles may comprise three or more different sizes (e.g., onerelatively larger size and two or more relatively smaller sizes),without limitation. The resulting polycrystalline diamond formed fromHPHT sintering the aforementioned diamond particles may also exhibit thesame or similar diamond grain size distributions and/or sizes as theaforementioned diamond particle distributions and particle sizes.Additionally, in any of the embodiments disclosed herein, the superhardbearing elements may be free-standing (e.g., substrateless) and formedfrom a polycrystalline diamond body that is at least partially or fullyleached to remove a metal-solvent catalyst initially used to sinter thepolycrystalline diamond body.

In some instances and for certain types of polycrystalline diamond, highthermal load on the superhard bearing elements 130 may producetemperatures that damage the superhard table 170, which may degrade ordeteriorate the superhard table 170. For example, the superhard table170 may comprise a polycrystalline diamond compact. Consequently, attemperatures of above around 700° C., the polycrystalline diamond maydegrade under normal operating conditions, which may lead to the failureof the superhard bearing elements 130 and, thus, of the thrust-bearingassembly 110. Therefore, maintaining the operating temperature of thesuperhard bearing elements 130 below detrimental temperatures, bydistributing the thermal load among all or many of the superhard bearingelements 130 through the thermally-conductive structure 160, may prolongthe useful life of the thrust-bearing assembly 110.

In some embodiments, the thermally-conductive structure 160 may includea thermally-conductive element 190 and/or an optional post 200, whichmay include any number of suitable thermally-conductive materials. Theoptional post 200 may be coupled to or in contact with thethermally-conductive element 190. In any event, the optional post 200may be in thermal communication with the thermally-conductive element190. Examples of thermally-conductive materials for thethermally-conductive structure 190 and optional post include, but arenot limited to, copper and copper alloys, aluminum and aluminum alloys,brass, bronze, gold, silver, graphite, diamond (e.g., polycrystallinediamond), and combinations thereof. For example, thethermally-conductive element 190 may be made from a material having athermal conductivity that is about 5 to about 50 times (e.g., about 10to about 25 times, about 15 to about 20 times, or about 18 to about 25times) greater than that of the material from which the support ring 151is made. For example, the material from which the thermally-conductiveelement 190 is made may exhibit a thermal conductivity at about 25° C.of about 200 W/m·K to about 2000 W/m·K, such as about 300 W/m·K to about1800 W/m·K, about 350 W/m·K to about 450 W/m·K, or about 1500 W/m·K toabout 1850 W/m·K. Moreover, various components and/or elements of thethrust-bearing assembly 110 can have varying yield strengths andfracture toughness, as described in more detail in U.S. application Ser.No. 13/281,681, the disclosure of which is incorporated herein, in itsentirety, by this reference.

In at least one embodiment, the thermally-conductive element 190 may besubstantially unitary. For example, the thermally-conductive element 190may be a cylindrical ring, which may fit into a slot formed in thesupport ring 151. In other embodiments, the thermally-conductive element190 may include multiple segments in thermal communication with eachother as well as in thermal communication with the optional posts 200.

The support ring 151 may include a material that has higher strength(e.g., greater tensile strength, greater shear strength, greaterhardness, etc.) than the thermally-conductive material that forms thethermally-conductive element 190. Similarly, in some instances, thethermally-conductive materials that form the thermally-conductiveelement 190 may have insufficient strength, rigidity, abrasionresistance, or a combination of such physical properties to facilitateoperation in harsh environments. Accordingly, the support ring 151 mayprovide greater support to the superhard bearing elements 130, such thatthe thrust-bearing assembly 110 may withstand higher loads thereon.Hence, in some embodiments, the thermally-conductive structure 160,which may comprise one or more thermally-conductive materials, may befully encased within the support ring structure 150 and/or superhardbearing elements 130. For example, the thermally-conductive element 190may be encased between the support ring 151 and retention ring 152 ofthe support ring structure 150. As such, the support ring 151 andretention ring 152 may protect or shield the thermally-conductiveelement 190 from certain harsh environments.

As discussed above, the support ring 151 and/or retention ring 152 mayprovide sufficient structural support for the superhard bearing elements130. As certain thermally-conductive materials may be substantiallysofter than the materials used in the support ring 151 and/or retentionring 152. Accordingly, the support ring 151 and/or the retention ring152 may provide most of the structural support and rigidity for thethrust-bearing assembly 110. In an embodiment, the thermally-conductiveelement 190 may comprise copper, while the support ring 151 may comprisealloy steel. In the absence of the support ring 151, the copperthermally-conductive element 190 may provide insufficient support to thesuperhard bearing elements 130 under operational forces, which may leadto deformation of the thrust-bearing assembly 110. Moreover, in someembodiments, the support ring 151 is sized and configured in a mannerthat at least a portion of the support ring 151 is positioned under abottom of the superhard bearing elements 130 (e.g., under the substrate180 of the superhard bearing elements 130), such as to providesufficient support therefor.

Also, a portion of the substrate 180 may be thermally-conductive and/orin thermal communication with the thermally-conductive element 190. Inone embodiment, the substrate 180 may at least partially enclose andprotect the optional post 200 from certain harsh environments. Hence, inat least one example, the substrate 180 comprises a tungsten carbidesection 210 and the optional post 200. The tungsten carbide section 210may shield the optional post 200 from the environment. Moreover, thetungsten carbide section 210 may provide sufficient support to thesuperhard table 170. In some embodiments, the tungsten carbide section210 may be sized and configured such as to be positioned over and/or incontact with the support ring 151. Accordingly, the forces/pressureapplied at the bearing surface 132 may be transferred through thesuperhard table 170, to the tungsten carbide section 210, and to thesupport ring 151.

In one or more embodiments, the substrate 180 may comprise the tungstencarbide section 210 and the optional post 200 prior to forming orbonding the superhard table 170 to the substrate 180. For example, thesubstrate 180 may initially comprise a single material, such ascobalt-cemented tungsten carbide. After the superhard table 170 isformed or otherwise bonded onto the substrate, a portion of thesubstrate may be removed, and the optional post 200 may replace suchremoved portion of the substrate. For example, a blind hole may becreated in the substrate and the optional post 200 may be inserted andpress-fitted, brazed, or otherwise secured within the hole, therebyforming the substrate 180, which may comprise the optional post 200 andthe tungsten carbide section 210. In an embodiment, the optional post200 may be in physical contact with the superhard table 170.

As described above, the thermally-conductive structure 160 may transferthe heat from one or several superhard bearing elements 130 across allof the superhard bearing elements 130 of the thrust-bearing assembly110. Specifically, heat (which may be generated due to contact betweenthe bearing surfaces 132 and the opposing bearing surface(s)) may betransferred from the superhard table 170 to the optional post 200, andto the thermally-conductive element 190. Subsequently, the heat may bedistributed across all of the superhard bearing elements 130, as thethermally-conductive element 190 transfers heat to the optional posts200 of the corresponding superhard bearing elements 130. In other words,all or most of the superhard bearing elements 130 of the thrust-bearingassembly 110 may include optional posts 200, which can transfer heat toand/or from the superhard table 170.

In some embodiments, the superhard tables 170 may also bethermally-conductive. For instance, as mentioned above, the superhardtables 170 may comprise polycrystalline diamond. Accordingly, thesuperhard tables 170 of superhard bearing elements 130 may also aid indissipating heat from the thermally-conductive structure 160 and fromthe thrust-bearing assembly 110. In one example, the bearing surfaces132 of the low-load superhard bearing elements 130 may be exposed tofluid, such as drilling fluid. Accordingly, the heat may be transferredfrom the thermally-conductive element 190 to the optional post 200 andto the superhard tables 170 of the superhard bearing elements 130.Thereafter, the heat may be transferred from the superhard tables 170 ofthe superhard bearing elements 130 to the fluid, thus dissipating theheat from the superhard bearing elements 130 and from the firstthrust-bearing assembly 110.

In addition, the heat may be dissipated from the superhard tables 170 ofall of the superhard bearing elements 130, as the drilling fluidcontacts side portions of the superhard tables 170. Thus, distributingthe thermal load across all of the superhard bearing elements 130 mayincrease overall heat dissipation from the superhard tables 170 by thedrilling fluid. Consequently, the thermally-conductive structure 160 andthermally-conductive superhard tables 170 may reduce overall thermalload on the thrust-bearing assembly 110 as well as on the superhardbearing elements 130 thereof. As such, useful life and/or operatingconditions (e.g., load bearing) of the thrust-bearing assembly 110 maybe increased.

As described above, the thermally-conductive structure 160 may comprisethe thermally-conductive element 190 and the optional post 200 and maybe configured in a manner that distributes the thermal load from one ormore of the superhard bearing elements 130 to all or most of thesuperhard bearing elements 130 of the first thrust-bearing assembly 110.It should be appreciated, however, that thermally-conductive structure160 may have any number of suitable configurations that may transferheat from one or more of the superhard bearing elements 130 to othersuperhard bearing elements 130, which may vary from one embodiment toanother. For instance, another embodiment of a thermally-conductivestructure is illustrated in FIG. 3A.

In particular, FIG. 3A illustrates a thrust-bearing assembly 110 a thatincorporates a thermally-conductive structure 160 a, which may include athermally-conductive element 190 a. Except as otherwise describedherein, the thrust-bearing assembly 110 a and its components andelements may be similar to or the same as thrust-bearing assembly 110(FIGS. 2A and 2B) and its respective components and elements. Thethrust-bearing assembly 110 a includes a plurality of superhard bearingelements 130 a positioned about a thrust axis 10 a.

The thrust-bearing assembly 110 a also may include a support ringstructure 150 a, which may support and carry the superhard bearingelements 130 a. More specifically, the support ring structure 150 a mayhave a plurality of recesses 153 a within which the superhard bearingelements 130 a may be secured. As noted above, among other ways ofsecuring the superhard bearing elements 130 a to the support ringstructure 150 a, embodiments disclosed herein may include the superhardbearing elements 130 a being press-fitted into the recesses 153 a orbrazed to the thermally-conductive element 190 a. However, in otherembodiments, the recesses 153 a of the thermally-conductive element 190a may be countersunk through holes similar to that shown in FIG. 2B andthe superhard bearing elements 130 a may include a shoulder or othergeometric feature that helps retain the superhard bearing elements 130in cooperation with the thermally-conductive element 190 a.

Additionally, the support ring structure 150 a may include a supportring 151 a that supports the superhard bearing elements 130 a.Furthermore, the support ring 151 a may be at least partially surroundedby or encased in a thermally-conductive element 190 a. Some instances,the thermally-conductive element 190 a may be a substantially uniform orunitary piece, which at least partially encases or encapsulates thesupport ring 151 a. In other words, in some embodiments, thethermally-conductive element 190 a may define the outer perimeter of thethrust-bearing assembly 110 a. In additional or alternative embodiments,the thermally-conductive element 190 a may define the opening of thethrust-bearing assembly 110 a.

As noted above, the support ring 151 a may comprise a material that hasa higher strength than the thermally-conductive material comprising thethermally-conductive element 190 a. Accordingly, the support ring 151 amay provide greater support to the superhard bearing elements 130 a,such that the first thrust-bearing assembly 110 a may withstand higherloads thereon. Thus, in at least one embodiment, a bottom surface of thesupport ring 151 a may be coplanar with or protrude past a bottomsurface of the thermally-conductive element 190 a. As such, the bottomsurface of the support ring 151 a may be coupled or secured to a supportsurface such that the support ring 151 a, such as to carry at least someof the load experienced by the superhard bearing elements 130 a.

In some embodiments, the support ring 151 a may be press-fitted into anopening or a channel in the thermally-conductive element 190 a.Additionally or alternatively, the support ring 151 a may be brazed,welded, fastened, or otherwise secured to the thermally-conductiveelement 190 a. In any event, the support ring 151 a and thethermally-conductive element 190 a may be coupled together.

Similar to the superhard bearing elements 130 (FIGS. 2A and 2B), thesuperhard bearing elements 130 a may comprise a superhard table 170secured to a substrate 180. In some embodiments, the substrate 180 maybe substantially uniform or unitary. For example, the substrate 180 maycomprise a unitary piece of cemented tungsten carbide. In anotherembodiment, the substrate 180 may comprise of one or more sections,which may vary from one embodiment to another. In some embodiments, thesubstrate 180 a may incorporate one or more thermally-conductiveportions, which may be in contact or otherwise in thermal communicationwith the thermally-conductive element 190 a. In any event, the substrate180 may be supported by the support ring 151 a, such that the forcesapplied to bearing surfaces 132 a of the superhard bearing elements 130a may be carried by the substrates 180 and by the support ring 151 a.

As described above, the thermally-conductive structure 160 a maycomprise the thermally-conductive element 190 a. More specifically, thethermally-conductive element 190 a may provide thermal communicationamong and between the superhard bearing elements 130 a of thethrust-bearing assembly 110 a. Accordingly, the thermally-conductivestructure 160 a may distribute the thermal load from one or more of thesuperhard bearing elements 130 a among all or substantially all of thesuperhard bearing elements 130 a of the thrust-bearing assembly 110 a.

In some embodiments, at least a portion of the superhard table 170 maybe in thermal communication with the thermally-conductive element 190 a.Thus, heat from one or more superhard bearing elements 130 a may betransferred from the superhard table 170 to the thermally-conductiveelement 190 a, and to other superhard bearing elements 130 a, therebydistributing the thermal load among a greater number of superhardbearing elements 130 a. In one embodiment, a portion of the superhardtable 170 may extend below a top surface of the thermally-conductiveelement 190 a, such that that portion of the superhard table 170 is incontact with the thermally-conductive element 190 a.

Moreover, as mentioned above, heat transferred from one or more of thesuperhard bearing elements 130 a among a greater number of the superhardbearing elements 130 a (e.g., all or substantially all of the superhardbearing elements 130 a) may improve cooling of the superhard bearingelements 130 a and of the thrust-bearing assembly 110 a. For example, asfluid (e.g., drilling fluid) passes about the superhard bearing elements130 a, the fluid can remove heat therefrom.

Moreover, as the fluid flows about the thermally-conductive element 190a, the fluid may remove heat from such thermally-conductive element 190a as well as from the superhard bearing elements 130 a, thereby coolingthe superhard bearing elements 130 a as well as the thrust-bearingassembly 110 a. In any case, the thermally-conductive structure 160 amay distribute heat from one or more superhard bearing elements 130 aamong additional superhard bearing elements 130 a of the thrust-bearingassembly 110 a. Consequently, the thermally-conductive structure 160 amay increase useful life or performance of the thrust-bearing assembly110 a (e.g., by avoiding damage to the superhard table 170).

The thickness of the superhard table 170 may vary according to variousembodiments. Moreover, in some embodiments, the support ring 151 a′ alsomay be a substrate for the superhard table 170. For example, FIG. 3Billustrates a thrust-bearing assembly 110 a′ that includes a supportring 151 a′ and superhard bearing elements 130 a′, which include thesuperhard table 170 coupled to and/or supported by the support ring 151a′. The superhard table 170, which may be optionally fully leached, mayreside directly on the support ring 151 a′. In other words, the entiresuperhard bearing element 130 a′ may comprise the superhard table 170 orsuperhard body. Furthermore, in any of the embodiments disclosed herein,a PDC may be replaced with a PCD slug, which may be optionally partiallyor substantially fully leached.

In some embodiments, the superhard table 170 may be secured to thesupport ring 151 a′. For example, the superhard table 170 may be brazedor otherwise secured to the support ring 151 a′. Also, in someembodiments, the support ring 151 a′ can include recesses that canreceive and/or restrain the superhard table 170 therein. Such recessesmay at least partially restrain the superhard table 170 from movingrelative to the support ring 151 a′.

It should be appreciated that the superhard table 170 may have anysuitable thickness. Moreover, in an embodiment, the outside surface ofthe superhard table 170 may be in physical and/or thermal contact orcommunication with the thermally-conductive element 190 a. As notedabove, the superhard table 170 may include thermally-conductive material(e.g., polycrystalline diamond). Accordingly, increasing the amount ofsurface of the superhard table 170 that is in thermal communication withthe thermally-conductive element 190 can increase the rate of heattransfer therebetween (e.g., through convection) and between thesuperhard bearing elements 130 a′ and the thermally conductive element190.

When the entire superhard bearing element 130 a′ comprises the superhardtable 170, the superhard bearing element 130 a′ may have the greatestamount of surface of the superhard table 170 in thermal communicationwith the thermally-conductive element 190. Such configuration maymaximize heat transfer between the superhard table 170 and thethermally-conductive element 190. The amount of surface of the superhardtable 170 in thermal communication with the thermally-conductive element190 may increase or decrease with corresponding increase or decrease inthe thickness of the superhard table 170.

Furthermore, in an embodiment, the superhard bearing element 130 a′ mayinclude a substrate (not shown) that supports the superhard table 170.Such substrate may be at least partially covered by the superhard table170. In other words, the superhard table 170 may surround the substratein a manner that at least a portion of the outside surface of thesuperhard bearing element 130 a′ is formed by the superhard table 170.Consequently, the superhard table 170 may be thinner closer to thecenter of the superhard bearing element 130 a′ and may be thicker closerto the outer edge(s) of the superhard bearing element 130 a′, in amanner that increases or maximizes the amount of the surface of thesuperhard table 170 that is in thermal communication with thethermally-conductive element 190.

Although thermally-conductive element, structure, or structurescontemplated herein may comprise a single or unitary piece, it should beappreciated that in other embodiments the thermally-conductive element,structure, or structures may exhibit other configurations. For example,as illustrated in FIG. 4, a thrust-bearing assembly 110 b mayincorporate a thermally-conductive structure 160 b that comprises aplurality of thermally-conductive elements 190 b. Except as otherwisedescribed herein, the thrust-bearing assembly 110 b and its materials,components, or elements (e.g., bearing elements) may be similar to orthe same as any of the thrust-bearing assemblies 110, 110 a (FIGS.2A-3A) respective components, materials, or elements.

In some embodiments, each of the plurality of the thermally-conductiveelements 190 b may surround each of a plurality of superhard bearingelements 130 b. Furthermore, the thermally-conductive elements 190 b maybe in thermal communication with each other. Accordingly, thethermally-conductive elements 190 b may transfer heat from one superhardbearing element 130 b to another, adjacent superhard bearing element130. Thus, the thermally-conductive elements 190 b may distribute theheat from one or more superhard bearing elements 130 b to a greaternumber of the superhard bearing elements 130 b, such as among all orsubstantially all of the superhard bearing elements 130 b. In anembodiment, any one of the thermally-conductive elements 190 b. In anadditional or alternative embodiment, some, most, or all of thethermally-conductive elements 190 may be coupled or connected to one ormore of the adjacent thermally-conductive elements 190. For instance,adjacent thermally-conductive elements 190 may be brazed, welded, orotherwise secured or coupled together.

In one or more embodiments, the thrust-bearing assembly 110 a mayinclude a support ring structure 150 b, which may secure and/or supportthe superhard bearing elements 130 b therein. In particular, the supportring structure 150 b may comprise a support ring 151 b, which includes aplurality of recesses 153 b therein. As noted above, the superhardbearing elements 130 b may be press-fitted, brazed, fastened, orotherwise secured in the recesses 153 b. Moreover, the superhard bearingelements 130 b may be press fitted, brazed, or otherwise secured withinthe recesses 153 b together with the thermally-conductive elements 190b. Accordingly, the thermally-conductive elements 190 b may be at leastpartially insulated and/or protected from external or operatingenvironment by the support ring 151 b.

In some embodiments, the superhard bearing elements 130 b may comprise asuperhard table 170 bonded to the substrate 180. In one example, thesubstrate 180 may be a solid or unitary block of material, such astungsten carbide or other suitable material. Moreover, the superhardtable 170 may be in thermal communication and/or otherwise in contactwith the thermally-conductive element 190 b, such that the heat may betransferred from superhard table 170 b to the thermally-conductiveelement 190 b.

In other embodiments, the substrate 180 may comprise multiple materials,which may include one or more thermally-conductive materials.Furthermore, the thermally-conductive materials of the substrate 180 maybe in contact or in thermal communication with the thermally-conductiveelements 190 b. In any event, however, the superhard bearing elements130 b may be in thermal communication with the thermally-conductiveelements 190 b and a manner that allows the heat to be transferred fromone or more of the superhard bearing elements 130 b to all orsubstantially all of the superhard bearing elements 130 b of thethrust-bearing assembly 110 b.

Although the above embodiments were described in connection with thethrust-bearing apparatuses and assemblies, it should be appreciated thatother embodiments are directed radial-bearing apparatuses andassemblies. FIG. 5 illustrates an embodiment of a radial-bearingapparatus 300. The concepts used in the thrust-bearing assemblies andapparatuses described above also may be employed in radial-bearingassemblies and apparatuses. Furthermore, except as otherwise describedherein, materials, components, or elements of the radial-bearingapparatus 300 may be similar to or the same as materials, components, orelements of various embodiments of the thrust-bearing apparatus orassemblies 100, 110, 110 a, 110 b, described above.

For instance, the radial-bearing apparatus 300 may comprise a firstradial-bearing assembly 310 (i.e., an outer race) and a secondradial-bearing assembly 320 (i.e., an inner race). The firstradial-bearing assembly 310 and the second radial-bearing assembly 320may be configured to allow relative rotation thereof about a rotationaxis 10 b. More specifically, in some instances, the firstradial-bearing assembly 310 may be a stator (i.e., may remain coupled orfixed to a stationary element or component of a machine or mechanism)and the second radial-bearing assembly 320 may be a rotor, coupled to arotating element or component of a machine or mechanism.

For example, the first radial-bearing assembly 310 may be fixed orcoupled to the housing of the subterranean drilling system and thesecond radial-bearing assembly 320 may be fixed or coupled to the outputshaft of the subterranean drilling system, as further described below.Alternatively, the second radial-bearing assembly 320 may be a stator,while the first radial-bearing assembly 310 may be a rotor that mayrotate relative to the stator or about the second radial-bearingassembly 320. In any event, the first radial-bearing assembly 310 andsecond radial-bearing assembly 320 may facilitate rotation of elementsor components of a machine about the rotation axis 10 b, whilepreventing or limiting lateral movement of such elements or componentsrelative to each other as well as relative to the rotation axis 10 b.

In some embodiments, the first radial-bearing assembly 310 and thesecond radial-bearing assembly 320 may include bearing elements, such assuperhard bearing elements 330 (e.g., superhard bearing elements 330 a,330 b). In particular, the superhard bearing elements 330 may be securedto respective support ring structures 340, 350. The superhard bearingelements 330 also may be positioned about the rotation axis 10 b. Forexample, the superhard bearing elements 330 may be positionedcircumferentially about the rotation axis 10 b. Moreover, in anembodiment, the support ring structure 350 may define an opening or ahole 355, which may accept the shaft (e.g., the output shaft of thesubterranean drilling system) or a spindle. Additionally, such shaft maybe secured to the support ring structure 350 in a manner that allows theshaft to rotate about rotation axis 10 b together with the secondradial-bearing assembly 320.

Similarly, the support ring structure 340 may define and outer perimeter(e.g., an outer diameter) of the first radial-bearing assembly 310.Furthermore, the support ring structure 340 may include support surfacesor areas that may couple or may be secured to a stationary portion of adevice or mechanism. For instance, the support ring structure 340 of thefirst radial-bearing assembly 310 may be fixedly secured to a housing ofthe subterranean drilling system. Accordingly, the radial-bearingapparatus 300 may facilitate rotation of the output shaft relative tothe housing about the rotation axis 10 b.

The superhard bearing elements 330 may be arranged in correspondingsingle rows about the support ring structures 340, 350. In additional oralternative embodiments, the superhard bearing elements 330 may bedistributed in two rows, three rows, four rows, or any other number ofrows. Furthermore, the superhard bearing elements 330 a, 330 b may bearranged in a manner that allows the superhard bearing elements 330 aand the superhard bearing elements 330 b to engage each other as thefirst radial-bearing assembly 310 and second radial-bearing assembly 320rotate relative to one another. In other words, the superhard bearingelements 330 a, 330 b may prevent or limit lateral movement of the firstradial-bearing assembly 310 and second radial-bearing assembly 320relative to each other, while allowing relative rotation thereof (e.g.,about the rotation axis 10 b).

Accordingly, at least one, some of, or each superhard bearing element330 a may include a superhard table (further described below) that has aconcave bearing surface 332 a (e.g., curved to form an interior surfaceof an imaginary tubular cylinder). Similarly, at least one, some of, oreach superhard bearing element 330 b may include a superhard table thathas a convex bearing surface 332 b (e.g., curved to form at least aportion of an exterior surface of an imaginary cylinder or sphere). Inany event, the concave bearing surface 332 a and the convex bearingsurface 332 b may be shaped, sized, positioned, and oriented togenerally correspond with and engage one another during operation of theradial-bearing apparatus 300.

The radial-bearing apparatuses may have one or more superhard bearingelements 330 that experience higher forces and/or friction than theother superhard bearing elements 330. For example, it is possible thatone or more superhard bearing elements 330 may extend or protruderelative to the imaginary cylindrical/spherical plane formed by theplurality of the superhard bearing elements 330 more than the othersuperhard bearing elements 330. Also in some instances, the rotationaxis 10 b may be oriented at a non-parallel angle relative to the vectorof the gravitational pull of the Earth. Accordingly, weight of themachine elements or unbalanced weight distribution of components coupledto or supported by the first radial-bearing assembly 310 and/or by thesecond radial-bearing assembly 320 may apply uneven forces to certainsuperhard bearing elements 330 as compared with other superhard bearingelements 330. For instance, the shaft connected to the secondradial-bearing assembly 320 and the housing securing the firstradial-bearing assembly 310 may be oriented approximately horizontallyor perpendicularly to the direction of Earth's gravitational pull. Assuch, the superhard bearing elements 330 positioned along a lowerportion of the radial-bearing apparatus 300 (i.e., below a horizontalcenterline of the radial-bearing apparatus 300) may experience higherforces and/or friction than the superhard bearing elements 330positioned along an upper portion of the radial-bearing apparatus 300.

Consequently, as mentioned above, one or more superhard bearing elements330 also may experience higher thermal loads thereon than othersuperhard bearing elements 330. Thus, in at least one embodiment, thefirst radial-bearing assembly 310 and/or second radial-bearing assembly320 may incorporate a thermally-conductive structure. Thethermally-conductive structure may distribute the thermal load from oneor more superhard bearing elements 330 among additional (e.g., all orsubstantially all) superhard bearing elements 330. Hence, for example,the superhard bearing elements 330 may limit operational temperatures,which may limit or prevent damage or degradation of the superhardbearing elements 330.

For instance, FIG. 6A illustrates an embodiment of the firstradial-bearing assembly 310 that incorporates a thermally-conductivestructure 360 a. As noted above, the thermally-conductive structure 360a may distribute the thermal load from a single or a few superhardbearing elements 330 a among multiple superhard bearing elements 330 aof the first radial-bearing assembly 310. Accordingly, thethermally-conductive structure 360 a may be in thermal communicationwith all or substantially all of the superhard bearing elements 330 a ofthe first radial-bearing assembly 310.

In some embodiments, the superhard bearing elements 330 a may include asuperhard table 370 a and a substrate 380 a. The superhard table 370 amay be similar to or the same as superhard table 170 and substrate 380 amay be similar to or the same as substrate 180 (FIG. 2B), as describedabove. Optionally, the substrate 380 a may include an optional post 400a. For example, the substrate 380 a may include a tungsten carbidesection 410 a and the optional post 400 a. The optional post 400 a maybe press-fitted, brazed or otherwise secured to and/or in the tungstencarbide section 410 a, as described above.

Moreover, the optional post 400 a may be in thermal communication withthe superhard table 370 a. Accordingly, heat may be transferred from thesuperhard table 370 a to the optional post 400 a and vice versa. Theoptional post 400 a also may be in thermal communication with thethermally-conductive element 390 a. Particularly, thethermally-conductive element 390 a together with the optional post 400 amay form the thermally-conductive structure 360 a that may conduct ortransfer the heat away from a single or few superhard bearing elements330 a and distribute it among additional the superhard bearing elements330 a.

In addition, the support ring structure 340 of the first radial-bearingassembly 310 includes a support ring 341. The support ring 341 mayprovide sufficient support to the superhard bearing elements 330 a.Moreover, the support ring 341 may include recesses 342, which may holdthe superhard bearing elements 330 a. For example, the superhard bearingelements 330 a may be press-fitted, brazed, or otherwise secured in thecorresponding recesses 342. Additionally or alternatively, the superhardbearing elements 330 a may be brazed, welded, screwed, or otherwisesecured to the support ring 341 in any number of suitableconfigurations.

Furthermore, in some embodiments, at least a portion of the substrate380 a may abut a bottom of the recess 342. For instance, the tungstencarbide section 410 a may abut the support ring 341, such that thesupport ring 341 may provide sufficient support to the superhard bearingelements 330 a. In other words, the structural load may be carried byand transferred from the concave bearing surface 332 a to the superhardtable 370 a, to the tungsten carbide section 410 a, and to the supportring 341.

The support ring 341 may comprise a material that has sufficientstrength to support to the superhard bearing elements 330 a. The supportring 341 may comprise alloy steel, other suitable materials, and/or anymaterials described above with respect to support ring 151 (FIG. 2B).Moreover, the material comprising support ring 341 may be substantiallyless thermally conductive than the materials comprising thethermally-conductive element 390 a.

In an embodiment, the thermally-conductive element 390 a may besubstantially unitary (e.g., ring-like) and may be coupled or otherwisesecured to or within the support ring 341. For example, thethermally-conductive element 390 a may be positioned at least partiallywithin a recess or a partial opening (e.g., a blind hole) within thesupport ring 341. In one embodiment, the thermally-conductive element390 a may be compressed from a first diameter, which may be greater thanthe outer perimeter of the support ring 341, to a second diameter, suchthat the thermally-conductive element 390 a is secured (e.g., press-fit)within the support ring 341.

In additional or alternative embodiments, the thermally-conductiveelement 390 a may comprise multiple segments in thermal communicationwith each other as well as in thermal communication with the superhardbearing elements 330 a. Such multiple segments also may be secured to orwithin the support ring 341. Also, the thermally-conductive element 390a may be machined to size, such as to match the outer diameter of thesupport ring 341. In any case, the thermally-conductive element 390 amay be sufficiently coupled to (e.g., brazed, press-fit, mechanicallyattached, etc.) the support ring 341, in a manner that allows thethermally-conductive element 390 a to remain coupled to the support ring341 during operation of the first radial-bearing assembly 310.

As mentioned above, the first radial-bearing assembly 310 may bepositioned within the second radial-bearing assembly 320, such that theconcave bearing surfaces 332 a of the superhard bearing elements 330 aengage the convex bearing surfaces 332 b of the superhard bearingelements 330 b. Except as otherwise described herein, materials,components and elements (e.g., bearing elements) of the secondradial-bearing assembly 320 may be similar to or the same as thematerials, components and elements of the first radial-bearing assembly310 as described above (FIG. 6A). In some embodiments, similar to thefirst radial-bearing assembly, the second radial-bearing assembly 320also may include a thermally-conductive structure 360 b, which maydistribute heat from one or several of the superhard bearing elements330 b among additional superhard bearing elements 330 b.

For instance, the thermally-conductive structure 360 b may include athermally-conductive element 390 b that may be in thermal communicationwith the superhard bearing elements 330 b. As such, thethermally-conductive element 390 b may distribute and/or equalize thethermal load among all or substantially all of the superhard bearingelements 330 b. In an embodiment, the thermally-conductive element 390 bmay be a ring-like element, which may be in thermal communication withan optional post 400 b. More specifically, the superhard bearingelements 330 b may comprise a superhard table 370 b coupled or bonded toa substrate 380 b, which may include the optional post 400 b.

Additionally, the support ring structure 350 of the secondradial-bearing assembly 320 may have a support ring 351, which mayprovide structural support to the superhard bearing elements 330 b. Inan embodiment, the support ring 351 may have one or more recesses 352,within which the superhard bearing elements 330 b may be secured to thesupport ring 351. Also, the support ring 351 may hold and/or secure thethermally-conductive element 390 b. For example, the support ring 351may include a slot or a channel that may hold and secure thethermally-conductive element 390 b. In some embodiments, thethermally-conductive element 390 b may be secured inside an innerchannel within the support ring 351. As such, the thermally-conductiveelement 390 b also may at least partially form or define the inside ofthe opening in the support ring 351, which may, for example, accept ashaft therein.

In at least one embodiment, the thermally-conductive element 390 b maybe substantially unitary. For instance, the thermally-conductive element390 b may be press-fit into and/or brazed to the channel in the supportring 351. Alternatively, the thermally-conductive element 390 b maycomprise multiple segments in thermal communication with each other.Optionally, such segments may be welded, brazed, or otherwise connectedto one another. Furthermore, the thermally-conductive element 390 b mayhave any number of other suitable sizes and configurations. In any case,as mentioned above, the thermally-conductive element 390 b may transferheat from one or more superhard bearing elements 330 b to othersuperhard bearing elements 330 b.

As noted above, the thrust-bearing apparatus 100 (FIG. 1) and/or theradial-bearing apparatus 300 (FIG. 5) may be used in any number ofmechanisms and mechanical systems. For instance, the thrust-bearingapparatus 100 and/or the radial-bearing apparatus 300 (FIGS. 1, 5) maybe used in a subterranean drilling system. An embodiment of asubterranean drilling system is illustrated in FIG. 7. Specifically, oneor more embodiments are directed to a subterranean drilling system 500that has a housing 510 enclosing a downhole drilling motor 520 (e.g., amotor, turbine, or any other device capable of rotating a shaft). Thedrilling motor 520 may be operably connected to an output shaft 530.

In some embodiments, the subterranean drilling system 500 also mayinclude a thrust-bearing apparatus 100, which also may be operablycoupled to the downhole drilling motor 520. The thrust-bearing apparatus100 may include the first thrust-bearing assembly 110 (a stator) thatdoes not rotate and a second thrust-bearing assembly 120 (a rotor) thatis attached to the output shaft 530 and rotates therewith. As mentionedabove, the thrust-bearing apparatus 100 may prevent or limit relativeaxial motion of the output shaft 530, while allowing the output shaft530 to rotate relative to the housing 510.

In additional or alternative embodiments, the subterranean drillingsystem 500 may include the radial-bearing apparatus 300. In particular,the radial-bearing apparatus 300 may have the first radial-bearingassembly 310 (a stator) and the second radial-bearing assembly 320 (arotor). The second radial-bearing assembly 320 may be coupled to theoutput shaft 530 in a manner that the second radial-bearing assembly 320may engage the first radial-bearing assembly 310. Moreover, in someembodiments, the first radial-bearing assembly 310 may be coupled to thehousing 510 in a manner that substantially prevents the firstradial-bearing assembly 310 from moving relative to the housing 510.Hence, the radial-bearing apparatus 300 may prevent or limit relativelateral motion of the output shaft 530 and housing 510, while allowingthe output shaft 530 to rotate relative to the housing 510.

Although the illustrated embodiment of the subterranean drilling system500 provides single thrust-bearing apparatus 100 and a singleradial-bearing apparatus 300, it is to be appreciated that the number ofthe thrust-bearing apparatuses, if any, and/or radial-bearingapparatuses, if any, may vary from one embodiment to another.Accordingly, the subterranean drilling system 500 may include multiplethrust-bearing apparatuses, which may be located along the length of thehousing 510 and/or output shaft 530 thereof. Likewise, the subterraneandrilling system 500 also may include multiple radial-bearingapparatuses, which may be located along the length of the housing 510and/or the output shaft 530 thereof. Also, the subterranean drillingsystem 500 may include only a single thrust-bearing apparatus 100 or asingle radial-bearing apparatus 300.

The subterranean drilling system 500 also includes a rotary drill bit540 configured to engage a subterranean formation and drill a borehole.Particularly, the rotary drill bit 540 may be connected to the outputshaft 530 in a manner that the output shaft 530 rotates the rotary drillbit 540. As the rotary drill bit 540 rotates and engages thesubterranean formation, the rotary drill bit 540 may drill the boreholetherein. In the illustrated embodiment, the rotary drill bit 540 isshown as a “roller cone” type bit, which includes a plurality of rollercones 550. However, other types of rotary drill bits, such as “fixedcutter” drill bits also may be used.

As the borehole is drilled, pipe sections may be connected to thesubterranean drilling system 500 to form a drill string capable ofprogressively drilling the borehole to a greater depth within the earth.Moreover, in some instances, high pressure drilling fluid is circulatedthrough the drill string and power section (not shown) of the downholedrilling motor 520. The high pressure drilling fluid may begin tocirculate through the drill string prior to the rotary drill bit 540engaging the subterranean formations, which may generate torque androtate the output shaft 530 (and thus the rotary drill bit 540).

Unless rotated from above (e.g., by the drill rig rotary), the housing510 may remain stationary as the output shaft 530 may rotate togetherwith the rotary drill bit 540. When the rotary drill bit 540 engages theterrain and formations, such as on the bottom of the downhole, a thrustload may be generated. Such thrust load is commonly referred to as“on-bottom thrust,” which tends to press or force the output shaft 530in an axially upward direction relative to the housing 510 and compressthe thrust-bearing apparatus 100. In turn, the thrust-bearing apparatus100 prevents or limits the axial movement of the output shaft 530, asnoted above.

Additionally, the flow of the drilling fluid through the drill stringand through the power section may create what is commonly referred to as“off-bottom thrust,” which tends to press or force the output shaft 530in an axially downward direction relative to the housing 510. Athrust-bearing apparatus (similar to or the same as the thrust-bearingapparatus 100) may prevent or limit axial downward movement of theoutput shaft 530 relative to the housing 510 in response to theoff-bottom thrust. Thus, a thrust-bearing apparatus also may becompressed by the off-bottom thrust.

The drilling fluid used to generate the rotation of the output shaft 530and the rotary drill bit 540 may exit openings in the drill string(e.g., in the rotary drill bit 540) and returns to the surface. As such,the drilling fluid may carry cuttings of the subterranean formationthrough an annular space between the drilled borehole and thesubterranean drilling system 500. Furthermore, a portion of the drillingfluid may be diverted by the downhole drilling motor 520 to cool and/orlubricate the thrust-bearing apparatus 100 and/or the radial-bearingapparatus 300.

While various aspects and embodiments have been disclosed herein, otheraspects and embodiments are contemplated. The various aspects andembodiments disclosed herein are for purposes of illustration and arenot intended to be limiting. Additionally, the words “including,”“having,” and variants thereof (e.g., “includes” and “has”) as usedherein, including the claims, shall be open ended and have the samemeaning as the word “comprising” and variants thereof (e.g., “comprise”and “comprises”).

What is claimed is:
 1. A bearing assembly, comprising: a support ringincluding at least one lateral surface; a plurality of polycrystallinediamond bearing elements each including a substrate comprising a carbidematerial and a polycrystalline diamond table bonded to the substrate,the plurality of polycrystalline diamond bearing elements are secured tothe support ring and distributed about an axis, each of the plurality ofpolycrystalline diamond elements including a polycrystalline diamondmaterial having a polycrystalline diamond bearing surface; athermally-conductive structure that is distinct from the substrate, thethermally-conductive structure is positioned in contact with at leastone lateral surface of the support ring and in thermal communicationwith at least one polycrystalline diamond bearing element of theplurality of polycrystalline diamond bearing elements; and wherein thethermally-conductive structure exhibits a higher thermal conductivitythan the support ring.
 2. The bearing assembly of claim 1, wherein thethermally-conductive structure is disposed in at least a portion of thesupport ring.
 3. The bearing assembly of claim 2, wherein the supportring includes a channel and the thermally-conductive structure is atleast partially positioned in the channel.
 4. The bearing assembly ofclaim 1, wherein at least a portion of the support ring is enclosed bythe thermally-conductive structure.
 5. The bearing assembly of claim 1,wherein the thermally-conductive structure is in direct contact with thepolycrystalline diamond material of the at least one polycrystallinediamond bearing element.
 6. The bearing assembly of claim 1, wherein thethermally-conductive structure at least partially surroundspolycrystalline diamond material of at least one polycrystalline diamondbearing element of the plurality of polycrystalline diamond elements. 7.The bearing assembly of claim 1, wherein at least a portion of thethermally-conductive structure is positioned inside at least onepolycrystalline diamond bearing element of the plurality ofpolycrystalline diamond elements.
 8. A bearing assembly, comprising: asupport ring; a plurality of polycrystalline diamond bearing elementssecured to the support ring and distributed about an axis, each of theplurality of polycrystalline diamond bearing elements including apolycrystalline diamond material having a polycrystalline diamondbearing surface; one or more thermally-conductive structures in thermalcommunication with the support ring and in thermal communication withpolycrystalline diamond material of at least one polycrystalline diamondbearing elements of the plurality of polycrystalline diamond bearingelements; and wherein: the one or more thermally-conductive structuresexhibit a higher thermal conductivity than the support ring; and the oneor more thermally-conductive structures at least partially surround thepolycrystalline diamond material of the at least one polycrystallinediamond bearing element; or the support ring includes a channel and theone or more thermally-conductive structures are at least partiallypositioned in the channel; or at least a portion of at least one of theone or more thermally-conductive structures is disposed inside the atleast one polycrystalline diamond bearing element.
 9. The bearingassembly of claim 8, wherein at least one of the one or morethermally-conductive structures is in direct contact with thepolycrystalline diamond material of the at least one polycrystallinediamond bearing element.
 10. The bearing assembly of claim 8, whereinthe one or more thermally-conductive structures include a plurality ofthermally-conductive structures distributed about the axis.
 11. Thebearing assembly of claim 10, wherein the plurality ofthermally-conductive structures are in thermal communication with oneanother.
 12. The bearing assembly of claim 11, wherein each of theplurality of thermally-conductive structures are in direct contact witheach directly adjacent thermally-conductive structure of the pluralityof thermally-conductive structures.
 13. The bearing assembly of claim 8,wherein the one or more thermally-conductive structures is disposed inat least a portion of the support ring.
 14. The bearing assembly ofclaim 8, wherein at least a portion of the support ring is surrounded bythe one or more thermally-conductive structures.
 15. A bearing assembly,comprising: a support ring; a plurality of polycrystalline diamondbearing elements secured to the support ring and distributed about anaxis, each of the plurality of polycrystalline diamond bearing elementsincluding a polycrystalline diamond table having a polycrystallinediamond bearing surface; one or more thermally-conductive structurespositioned in contact with at least one surface of the support ring andin contact with the polycrystalline diamond table of at least onepolycrystalline diamond bearing elements of the plurality ofpolycrystalline diamond bearing elements; and wherein: the one or morethermally-conductive structures exhibit a higher thermal conductivitythan the support ring; and at least one of the one or morethermally-conductive structures at least partially surrounds thepolycrystalline diamond table of the at least one polycrystallinediamond bearing element; or at least a portion of at least one of theone or more thermally-conductive structures is disposed inside the atleast one polycrystalline diamond bearing element.